唐岛湾网箱养殖区沉积物-水界面溶解无机氮的扩散通量

Diffusive Fluxes of Dissolved Inorganic Nitrogen Across Sediment-Water Interface in Net-Cage Culture Area of Tangdao Bay

2004-08-2005-05分4个航次对唐岛湾网箱养殖区的10个站的沉积物间隙水和上覆水中的溶解无机氮营养盐(NH4+-N、NO3--N、NO2--N)进行了现场调查,并使用Fick第一定理对该海区沉积物-水界面溶解无机氮的扩散通量进行了估算.结果表明,网箱养殖区的上覆水和沉积物间隙水中溶解无机氮均以NO3--N为主,分别占溶解无机氮总量的73.34%和61.45%;上覆水中溶解无机氮(DIN)和NO3--N含量的季节变化趋势一致,在2004-10达到峰值,NH4+-N的季节变化稍有不同;间隙水中溶解无机氮(DIN)和NO3--N、NH4+-N的变化趋势一致,表现为从5月份到8月份含量逐渐增加,到10月份达到最大,然后到次年2月份又减少;上覆水和间隙水中NO2--N的含量随养殖进程表现为一个逐步积累的过程.NH4+-N、NO3--N和NO2--N在沉积物-海水界面上的扩散通量分别为5.46、-5.04、8.71μmol/(m2.d),NO2--N的扩散释放对唐岛湾网箱养殖区的水环境质量影响较大.

On basis of field data measured during 4 cruises from August 2004 to May 2005, concentrations of NH4^＋ -N, NO3^- -N, NO2^- -N in overlying and interstitial waters of sediments in net-cage culture areas of Tangdao Bay were analyzed. Moreover, diffusive fluxes of dissolved inorganic nitrogen from sediments were estimated by Fick＇s first law. Results showed that the main form of inorganic nitrogen in overlying and interstitial waters of sediments was NO3^- -N, accounting for 73.34 % and 61.45 % respectively. Concentrations distributions of dissolved inorganic nitrogen （DIN） and NO3^- -N in overlying water varied seasonally, which got their maximum concentration in October 2004 while the NH4^＋ -N concentration showed a little difference. The seasonal change of dissolved inorganic nitrogen （DIN） and NO3^- -N, NH4^- -N in interstitial water varied similarly and also got their maximum concentration in October 2004. The concentration of NO2^- -N in overlying and interstitial waters increased from spring to winter. The average fluxes of NH4^＋ -N, NO3^--N, NO2^--N were separately 5.46, -5.04,8.71 μmol/（m^2 ·d）. And NO2^- -N was the most diffusive flux component in net-cage culture area of Tangdao Bay.